Masanori Nakahara

A novel gain-of-function mutation of c-kit gene in gastrointestinal stromal tumors

BACKGROUND & AIMS The c-kit gene encodes a receptor tyrosine kinase (KIT). Recently, we found gain-of-function mutations of the c-kit gene in gastrointestinal stromal tumors (GISTs). All mutations were confined within the 11 amino acids (Lys-550 to Val-560) in the juxtamembrane domain, but one GIST showed a novel deletion-type mutation at codon 579 (Asp) in the juxtamembrane domain. The aim of this study was to clarify whether the mutation is activating. METHODS Mutant c-kit cDNA was transfected into an interleukin 3 (IL-3)-dependent Ba/F3 murine lymphoid cell line, and the magnitude of autophosphorylation of the mutant KIT was examined with or without stem cell factor (SCF), a ligand of KIT. An in vitro kinase assay was also performed. The biological behavior of the transfectant was estimated by both an in vitro proliferation assay and in vivo transplantation to nude mice. RESULTS The mutant KIT exhibited constitutive phosphorylation and strong kinase activity without SCF. The transfectant grew autonomously without IL-3 and SCF, and it formed tumors in nude mice. CONCLUSIONS Deletion at codon 579 (Asp) in the juxtamembrane domain of the c-kit gene is a novel gain-of-function mutation other than the region between Lys-550 and Val-560.

Scheduled endoscopic surveillance controls secondary cancer after curative endoscopic resection for early gastric cancer: a multicentre retrospective cohort study by Osaka University ESD study group

Background After endoscopic submucosal dissection (ESD) of early gastric cancer (EGC), patients are at high risk for synchronous or metachronous multiple gastric cancers. Objective To elucidate the time at which multiple cancers develop and to determine whether scheduled endoscopic surveillance might control their development. Design A multicentre retrospective cohort study from 12 hospitals was conducted. Patients with EGC who underwent ESD with en bloc margin-negative curative resection were included. Synchronous cancer was classified as concomitant cancer or missed cancer. The cumulative incidence of metachronous cancers and overall survival rate were calculated using the Kaplan–Meier method. Results From April 1999 to December 2010, 1258 patients met the inclusion criteria. Synchronous or metachronous multiple cancers were detected in 175 patients (13.9%) during a mean of 26.8 months. Among the 110 synchronous cancers, 21 were missed at the time of the initial ESD. Many of the missed lesions existed in the upper third of the stomach and the miss rate was associated with the endoscopists inexperience (<500 oesophagogastroduodenoscopy cases). The cumulative incidence of metachronous cancers increased linearly and the mean annual incidence rate was 3.5%. The incidence rate did not differ between patients with or without Helicobacter pylori eradication. Four lesions (0.32%) were detected as massively invading cancers during the follow-up. Conclusions Nineteen per cent of synchronous cancers were not detected until the initial ESD. The incidence rate of metachronous cancer after ESD was constant. Scheduled endoscopic surveillance showed that almost all recurrent lesions were treatable by endoscopic resection.

Deficiency of KIT-positive cells in the colon of patients with diabetes mellitus.

Diabetes mellitus is a well‐known cause of gastrointestinal dysmotility. The pathogenesis of diabetic gastroenteropathy is mainly considered to be a neuropathy, but the cause of dysmotility remains unknown. Interstitial cells of Cajal (ICC), which express c‐kit receptor tyrosine kinase (KIT), are considered to be pacemaker cells for the gastrointestinal movement. Therefore, we investigated a possible involvement of ICC in the pathogenesis of diabetic gastroenteropathy in humans.

c-kit gene mutation at exon 17 or 13 is very rare in sporadic gastrointestinal stromal tumors.

Background and Aim:  Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumors of the human gut. They frequently have gain‐of‐function mutations of the c‐kit gene, which encodes a receptor, tyrosine kinase. The mutations were found at exon 11 in most cases, and either at exon 9 or at exon 13 in rare cases. Recently, we found a family with multiple GIST and a gain‐of‐function mutation at exon 17. The family was the first reported GIST case with c‐kit gene mutation at exon 17 including sporadic GIST. Although we previously reported that the c‐kit gene mutation at exon 17 was not detected in 124 sporadic GIST by single‐strand conformation polymorphism (SSCP) analysis, the mutation at exon 17 observed in the familial GIST was detectable by the use of direct sequencing but not by our SSCP method. In the present study, we examined the mutations at exon 17 and exon 13 by using direct sequencing.

Disturbed gastrointestinal motility and decreased interstitial cells of Cajal in diabetic db/db mice

Background and Aim:  Diabetes mellitus (DM) often causes gastrointestinal dysmotility. Interstitial cells of Cajal (ICC), which express c‐kit receptor tyrosine kinase (KIT), are considered the pacemaker cells for gastrointestinal movement. The present study was designed to determine the role of ICC in the pathogenesis of gastroenteropathy in type 2 DM.

Clinical outcomes of endoscopic submucosal dissection for superficial esophageal neoplasms: a multicenter retrospective cohort study

BACKGROUND AND STUDY AIMS The safety and efficacy of endoscopic submucosal dissection (ESD) for superficial esophageal neoplasms (SENs) have not been evaluated in a multicenter survey. The aim of this study was to investigate the clinical outcomes in a multicenter study that included municipal hospitals. PATIENTS AND METHODS Of 312 consecutive patients with 373 esophageal lesions treated by ESD at 11 hospitals from May 2005 to December 2012, a total of 368 SENs in 307 patients were retrospectively analyzed. RESULTS The median tumor size was 18 mm (range 2 - 85 mm). The median procedure time was 90 minutes (range 12 - 450 minutes). The en bloc resection and complete resection rates were 96.7 % (95 % confidence interval [CI] 94.4 % - 98.1 %) and 84.5 % (95 %CI 80.5 % - 87.8 %), respectively. Perforation (including mediastinal emphysema), postoperative pneumonia, bleeding, and esophageal stricture, occurred in 5.2 % (95 %CI 3.3 % - 7.9 %), 1.6 % (95 %CI 0.7 % - 3.5 %), 0 %, and 7.1 % (95 %CI 4.9 % - 10.2 %) of patients, respectively. All of these complications were cured conservatively. No procedure-related mortality occurred. Early treatment periods (odds ratio [OR] = 4.04; P < 0.01) and low volume institutions (OR = 3.03; P  = 0.045) were significantly independent risk factors for perforation. The circumference of the lesion was significantly associated with postoperative stricture (OR = 32.3; P < 0.01). The procedure times significantly decreased in the later period of the study (P < 0.01). Follow-up data (median 35 months; range 4 - 98 months) showed significant differences in overall survival (P = 0.03) and recurrence-free survival (P < 0.01) rates between patients with curative and noncurative resections. CONCLUSIONS Esophageal ESD has become feasible with acceptable complication risks and favorable long term outcomes.

An increased number of CD40-high monocytes in patients with Crohn’s disease

OBJECTIVE:CD40-CD40 ligand (CD40L) interaction is essential for the T-lymphocyte–dependent immune response. This interaction may be operational in the pathogenesis of inflammatory bowel diseases (IBD). The present study examined the expression of CD40 in peripheral blood mononuclear cells (PBMNCs) and tissue specimens, and CD40-stimulated interleukin (IL)-12 release from PBMNCs in IBD.METHODS:The expression of CD40 in PBMNCs and tissue inflammatory cells was examined by flowcytometry and immunohistochemistry, respectively. IL-12 release was measured in cultured media of PBMNCs by an enzyme-linked immunosorbent assay.RESULTS:Most peripheral blood B-lymphocytes expressed CD40 in all subjects. However, in ulcerative colitis (UC) patients, a significantly increased mean fluorescence intensity (MFI) of CD40 on B-lymphocytes was detected, compared with control subjects and patients with Crohns disease (CD). In contrast, both the percentage positivity and MFI of CD40 on monocytes of active CD subjects were significantly increased, compared with the other groups. In active CD patients, a high level of IL-12 release from PBMNCs was observed by CD40 stimulation, compared with those of the other groups. When primed with IFN-γ, PBMNCs from inactive CD patients released a significantly high level of IL-12, probably via stimulation by the CD40 monoclonal antibody. In the affected mucosa of CD, numerous CD40-positive cells were demonstrated, and they were also CD68-positive, suggesting these double CD40/CD68-positive cells are tissue macrophages.CONCLUSIONS:These results suggest that the examination of CD40 expression in PBMNCs might enable the differentiation of CD from UC. CD40-high monocytes in CD patients may play a role in the pathogenesis of CD.

Dose-dependent and time-limited proliferation of cultured murine interstitial cells of Cajal in response to stem cell factor

Interstitial cells of Cajal (ICCs) play a role as pacemakers for gastrointestinal movement. Although some in vivo experiments showed that the c-kit receptor tyrosine kinase (KIT) and its ligand, stem cell factor (SCF), might be required for the development of murine ICCs near birth, in vitro experiments would be useful to clarify the role of SCF-KIT system for the development of ICCs. We attempted to establish a culture system in order to investigate the proliferation of ICCs. Murine gastrointestinal cells from embryos or neonates were cultured with SCF and stained with anti-KIT antibody and/or alcian-blue. The numbers of KIT+ cells a n d alcian-blue+ cells we re counted, and the number of KIT+.alcian-blue- cells, which represent ICCs was calculated. Clusters containing KIT+ cells were formed in culture. The number of KIT+.alcian-blue- cells from day-18 post coitum embryos increased in response to SCF up to a concentration of 50 ng/ml or for 8 days. The number of cells from day-2 post-partum neonates increased for 4 days, and then remained constant in the presence of SCF. In contrast, the number of cells from day-6 post-partum neonates did not increase and remained constant, even in the presence of SCF. ICCs showed a dose-dependent and time-limited proliferation in response to SCF in the in vitro culture system used here in.

Renal impairment during the treatment of telaprevir with peginterferon and ribavirin in patients with chronic hepatitis C

Renal damage has been reported as an important complication during combination treatment of peginterferon (PEG IFN), ribavirin (RBV) and telaprevir (TVR) for chronic hepatitis C. However, very little is known about this complication. We investigated the role TVR plays in renal damage during this triple therapy.

Utility of computed tomography fusion imaging for the evaluation of the ablative margin of radiofrequency ablation for hepatocellular carcinoma and the correlation to local tumor progression

To demonstrate the usefulness of the computed tomography (CT) fusion imaging for the evaluation of treatment effect of radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC).